Leaving your gadgets plugged in and charging has two drawbacks. One, you continue to draw juice when you don’t need it, to the general detriment of life on Earth. Second, it hardly helps with battery life.
As an HTC Desire HD owner, it’s the latter I worry about. Even with a perfectly healthy battery, the time between charges is …

Neat trick

Nice

Trouble with tribbles

My biggest problem with many of the claimed 'energy saving' devices is that they consume more power than the device which you are trying to off-set. Many of these standby saver switches consume >1W when many consumer devices sold in the past few years consume <1W in standby.

So, is this Green Zero consuming much energy to actually run the switch function? Is it less than the quiescent current of the device no longer being charged? When reviewing energy saving products I would like reviewers to check the energy consumption of them so they can be compared to not using them.

Output power?

The review unfortunately missed out what the output power was - would it charge an iPhone or iPad for example or does it only have a 500ma output? Also how efficient is it when charging - some power adapters are much more efficient than others?

Does it really extend battery life? Most smartphones will have circuitry to manage the charging themselves. Plus how would you know unless you specifically have equipment to measure the actual capacity of your cell now and then again in a year - but then again that would not work as you have nothing to accurately compare it with - i.e. if you had used the manufacturers charger?

The other big problem is - some people want their phones at 100% when they take them off the charger - with this you could get home and plug your phone in - leave it overnight and find it at 60% the next morning.

Eco friendly?

How eco friendly is this really if you buy this as well as the one you got free from the manufactuer - it may save you a bit of electricity but it's manufacture still costs resources for something you are duplicating.

Timer?

Surely this would be better if I could have some kind of timer system built in?

ie. either a setting that I plug my phone in on my bedside cabinet and, once full, it cuts off the power. At 6AM it then switches charging back on ready for me to get up at 6.30AM and have my phone on 100% again?

Or, perhaps an option that it would provide power every 3-hours for the device to charge back up to full.......

Question

With regards to the second part (overcharging bad for the battery), why the hell don't phone manufacturers build this functionality into the phone itself?? All my laptops have done this for the last 10 years, it baffles me that the phones don't do the same thing.

Errm, no

You aren't going to knacker your battery by leaving it "on charge", largely because you aren't leaving it on charge. Ever noticed how most devices have a little LED that changes colour when its fully charged (usually from amber to green). Yep, that's right, it manages its own charging and stops charging the battery when its full. It then continues to power itself from external DC until it is unplugged, ensuring that the battery is nice and full when you disconnect it.

Plug your phone into this thing and it will charge it up (over a couple or three hours) and then disconnect. At that point your phone is on battery. So you won't wake up to a fully charged phone.

Now, running your device on battery is *less* green than running it on mains power because of the inefficiencies in charging. As using this thing means your device is spending more time on battery power, it could actually be less "green" than merely relying on the device's internal charge regulator.

A tiny fraction is still a tiny fraction, even if you scale it up...

"Apparently if all the 70-odd million chargers in use worldwide were swapped out for Green Zeros it would save 47 million tons of carbon dioxide a year."

I'm guessing that as a percentage of my total energy usage, the bit that's wasted by my phone charger is almost unmeasurable.

Let's be nice though and say that it's 0.01% of my annual energy usage.

So, if everyone in the world used one of these devices, we'd save 0.01% of global energy use.

I.E. it's pointless to worry about how much your phone charger uses when you compare it to say central heating, ovens, cars etc. Make changes where they'll have a measurable effect - if you want to make a change.

Oh and with reference to the quote (above) - how much CO2 would be produced making and distributing (and disposing of) 70 million of these chargers?!

Great

Not so fast ...

"if all the 70-odd million chargers in use worldwide were swapped out for Green Zeros it would save 47 million tons of carbon dioxide a year"

Let's see if that's true. According to the Carbon trust, 1kWh of electricity releases 545.22g of CO2 into the atmosphere (not sure how they can be so precise, but anyhoo ...). Osun are saying that each charger is responsible for around 630kg of CO2 each year - that's 1,265kWh, or 3.465kWh per day. That means (even assuming every charger is left plugged in 7x24 - I'm sure *some* of them must be, but mine certainly aren't) an average of 150W, which is within the bounds of credibility, but sounds high to me.

You must have a dodgy battery then?

Lets assume you go to bed at 23:00 and plug your phone in to the green charger

Lets assume that you had a heavy day and it takes say 4 hours to charge your phone to full charge, thats 03:00

Lets assume you get up at 07:00

If you are telling me that leaving your phone sat on the bedside table for 4 hours will make the battery flat then there is something seriously wrong with your battery or the background tasks you have running!

Sleep time for ALL the little boys and girls

My Blackberry has a timer built in, so it switches off at 23:30, and back on at 6:05 with the alarm clock. (Pretty much) no power used, and the battery still at the same charge it had the night before.

You may already have an equally economical device or charger.

But it's nice to know. Or to have a spare.

Also, my Samsung Galaxy Tab 7 inch is quite hungry for power when it's charging, will this device satisfy it? Also has a funny cable port at the device end, so your arithmetic about plug choices is incorrect. USB-type socket on the charger itself.

Nonsense numbers

"Apparently if all the 70-odd million chargers in use worldwide were swapped out for Green Zeros it would save 47 million tons of carbon dioxide a year."

I'm inclined to think these numbers are nonsense. Firstly, only 70-odd million charges in a world of about 6.5bn people? Anyway, be that as it may, if we take those numbers at face value, that works out at two-thirds of a ton of CO2 per charger per year. Really? The embedded CO2 of one kWh of grid power in the UK is estimated as being a little over 0.5Kg. That would mean each of the existing chargers was responsible for about 1,300 kWh of electricity per year.

I think not - does anybody do a credibility check on these numbers before they get published? Somewhere somebody has slipped at least a couple of orders of magnitude.

Credibility checks.......

I cannot quite get my head around this.

You plug your phone into one of these overnight and it charges for 2 hours then cuts out. The phone is on battery for the remaining 6 hours which means that you need to charge your phone again 6 hours sooner than you would have.

Unless I am massively misunderstanding something the total amount of power you use over time is the same.

I was also under the impression that quick charging only was *detrimental* to battery life, and that a good trickle charge was a benefit.

Here is a thought; how many of us really need to keep our phones on overnight? Turn 'em off and save way more power than with a £15 plastic adapter....

Kills batteries.

This is basically the same as plugging your phone in - charging it up - when it hits 100% unplugging it so it's running off battery.

Based on most Android / iPhones you would wake up to find you are sitting at 60-70% charge and have to charge it up again. Frustration and wasted charge cycles. Using this as your main charger could result in almost double the charge cycles so the battery actually lasts half as long.

Fail.

This will result in more charge cycles (or partial ones) so will actually wear your battery out quicker = fail.

Most smartphone AC adapters will charge the phone then run the phone off the AC adapter thus keeping the battery at 100% and resulting in fewer charge cycles. This one charges to 100% - then your phone will discharge overnight - you wake in the morning and have to charge it up again.

Simple rule: Eco = expensive + inferior

What's a watt?

Some of the above commentors have obviously not been formally introduced to the watt. 150 watts is *not* within the bounds of credibility. That much power would be burning holes in one's bedside table. Think: one-and-a-half 100-watt incandescent light bulbs.

Since most USB chargers are basically at room temperature, it's obvious that they're not wasting even one watt. Think: a 7-watt Xmas tree bulb will burn your hand if gripped; that's what seven watts feels like.

And No! Buying one of these (even if it did make sense, which it doesn't) does not compensate for unnecessarily driving around in a big silly SUV.

Gobbledigook.

The charger switches itself off when the current drawn by the device it is charging drops below a certain threshold. All this means (for all but the most simplistic devices) is that the device under charge has switched from constant current to constant voltage charging. Your battery indicator may have all its bars lit but it has really only reached something like 80 or 85% of full charge.

You're not saving any net energy. You are simply charging the phone a little less each time. The prinicipal energy sink is the device itself ... how much energy you use depends on how much you use that, not how you charge the battery.

Not a bad idea

Phones don't run of AC when plugged in and fully charged, they still run off the battery - so the battery is continually cycling from 100% to 90 or 85-odd % and back up when plugged in unnecessarily. That reduces battery life. Far better to charge to 100% and unplug, which is what this does.

If you plug your phone in at midnight with 30% charge it will be fully charged by about 2am and unless it's polling data like there is no tomorrow at most your handset should lose 10-15% before 7.30am and that is assuming it's a power greedy Android smartphone. Something like a Nokia C5 would only loose about 5% if that.

Use this device to quickly top it up while having your cornflakes in the morning and bingo, full charge and you have only bounced the battery off the maximum twice in 24 hours. Over a long enough period of time this will keep your battery in a more healthy state.

As for the output, it's on the website - 5Vdc, 1000mA like all USB mains chargers.

I suspect the CO2 savings are calculated with the usual OEM-press-release magic calculator, that's why it says "apparently".

Of course if you charge your handset or iPod when it's switched off then this device should really work.

Viz the cable, the reviewer is right, it's doesn't come with one, at least the unit I was given didn't have one. Bit pricey at £15 though.

@AC 09:46

"Phones don't run of AC when plugged in and fully charged, they still run off the battery - so the battery is continually cycling from 100% to 90 or 85-odd % and back up when plugged in unnecessarily."

I'd rather 100% thank you.

"If you plug your phone in at midnight with 30% charge it will be fully charged by about 2am and unless it's polling data like there is no tomorrow at most your handset should lose 10-15% before 7.30am and that is assuming it's a power greedy Android smartphone. Something like a Nokia C5 would only loose about 5% if that."

Midnight is a bit late for me - so if you plug it in earlier you wake up with ~20-30% gone = not good. I'd rather have a phone with near enough 100% rather than risk it running out.

"As for the output, it's on the website - 5Vdc, 1000mA like all USB mains chargers."

Shame the reviewer forgot to include this really quite important information. I found it on the website as well but bit like a car review that neglects to tell you the 0-60 or MPG etc.

Really?

Cycles.

"Phones don't run of AC when plugged in and fully charged, they still run off the battery - so the battery is continually cycling from 100% to 90 or 85-odd % and back up when plugged in unnecessarily. That reduces battery life. Far better to charge to 100% and unplug, which is what this does."

So you are saying that 100% -> 95% done 4 times is any worse for a battery than 100% -> 80% once - lithium ion has no 'memory effect' so it shouldn't.

Yes it is worse!

"So you are saying that 100% -> 95% done 4 times is any worse for a battery than 100% -> 80% once - lithium ion has no 'memory effect' so it shouldn't."

Lithium ion may not have "memory effect" but that is not the relevant factor here. One of the key factors on overall battery life is the number of charge/discharge cycles any particular technology is good for. So 100% -> 95% done 4 times *IS* worse as you are using up 4 of your battery's charge/discharge lives rather than just 1.

Most probably incorrect.

"Phones don't run of AC when plugged in and fully charged"

That is most probably incorrect - for example Tekkeon make an iPhone battery case - here is their blurb:

"myPower for iPhone 4 preserves the iPhone battery by bypassing the battery and directly powering (rather than charging) iPhone 4. When plugged into a USB power adapter or computer USB port, myPower for iPhone 4 will simultaneously charge the connected iPhone 4 battery"

So it runs the iPhone off the Tekkeon battery first but does not charge the iPhone then when the Tekkeon battery is flat it would switch over to the iPhone battery.

If that battery pack can do it - would assume an AC charge would or at least could do it.